Carboxylic Acids & Polymers

physical properties of carboxylic acids

shorter chains dissolve in water due to H bonds, forms H bonds with other COOH molecules

biodiesel

• veg oil + CH3OH + KOH (catalyst) → biodiesel

• forms methyl ester (biodiesel) & glycerol

soap

made from fat/oil + NaOH → sodium salt (soap) + glycerol

veg oil

• is an ester

• has unsaturated (double bonds) fatty acid chains - do not pack closely together

• weaker van der waals - lower m.p.

• can show E/Z isomerism

animal fat

• is an ester

• solid at room temp - saturated fatty acid chains, chains pack closely → stronger van der waals

ester hydrolysis - base and acid

• acid: produces alcohol & COOH doesn't go to completion, eqm. established

• base: sodium salt + alcohol eqm. disrupted goes to completion

acid anhydride + water

2x carboxylic acid

acid anhydride + ammonia

amide + carboxylic acid

acid anhydride + alcohol

ester + carboxylic acid

acid anhydride + 1^o amine

N substituted amide + carboxylic acid

acyl chloride + water

carboxylic acid + white HCl fumes (vigorous reaction)

acyl chloride + ammonia

amide + white HCl fumes (vigorous reaction)

acyl chloride + alcohol

ester + white HCl fumes (vigorous reaction)

acyl chloride 1^o amine

N substituted amide + white HCl fumes (vigorous reaction)

why are acid anhydrides used instead of acyl chlorides in industry?

• less corrosive

• doesn’t produce HCl fumes

• doesn’t react as vigorously with water

• is cheaper

what is heating under reflux used for?

heating volatile liquids without loosing the products

reaction to make aspirin

ethanoic anhydride + salicylic acid → aspirin + ethanoic acid

Kevlar

• made from benzene -1,4- dicarboxylic acid 1,4-diaminobenzene

• is a polyamide with an amide link/bond

• used for bulletproof vests, car tyres - lightweight but very strong

nylon 6,6

• is a polyamide

• hexanedioic acid + 1,6 aminohexane

• used in ropes, fabric, carpet & parachute clothing

Terylene

• is a polyester

• benzene-1,4-dicarboxylic acid + ethane-1,2-diol

• used in plastic drink bottles, sheeting & clothes

condensation vs addition polymers

• condensation polymers have polar bonds - they can interact between chains forming H bonds

• condensation have higher m.p. due to H bonds & pdpd

• condensation are susceptible to attack from nucleophiles → biodegradable & water soluble

• addition polymers (polyalkenes) - saturated, usually non-polar & unreactive

• addition do not biodegrade quickly

disposal: landfill

used for plastics that:

• are difficult to recycle

• difficult to separate from other materials

• not enough plastic to extract to make extraction economically viable

→ landfill emits greenhouse gases, is expensive, not sustainable

→ risk of water contamination due to waste leaching

disposal: incineration

• energy released can be used as power

• release toxic fumes (PVC → HCl fumes)

• flue gases added to neutralise acidity

disposal: recycling

• remoulding plastics

• cracking plastics using monomers to make organic feedstock

recycling pros & cons

• pros: cheaper than making from scratch, less CO2 compared to incineration, reduces landfill use, preserves non renewable raw materials

• cons: plastics can be contaminated, wide variety of plastics can be difficult to recycle, difficult to remake original plastic from recycled material, sorting & processing plastic more expensive than incineration